Sea anemone peptide with uncommon ß-hairpin structure inhibits acid-sensing ion channel 3 (ASIC3) and reveals analgesic activity.

Three novel peptides were isolated from the venom of the sea anemone Urticina grebelnyi. All of them are 29 amino acid peptides cross-linked by two disulfide bridges, with a primary structure similar to other sea anemone peptides belonging to structural group 9a. The structure of the gene encoding the shared precursor protein of the identified peptides was determined. One peptide, π-AnmTX Ugr 9a-1 (short name Ugr 9-1), produced a reversible inhibition effect on both the transient and the sustained current of human ASIC3 channels expressed in Xenopus laevis oocytes. It completely blocked the transient component (IC50 10 ± 0.6 µM) and partially (48 ± 2%) inhibited the amplitude of the sustained component (IC50 1.44 ± 0.19 µM). Using in vivo tests in mice, Ugr 9-1 significantly reversed inflammatory and acid-induced pain. The other two novel peptides, AnmTX Ugr 9a-2 (Ugr 9-2) and AnmTX Ugr 9a-3 (Ugr 9-3), did not inhibit the ASIC3 current. NMR spectroscopy revealed that Ugr 9-1 has an uncommon spatial structure, stabilized by two S-S bridges, with three classical ß-turns and twisted ß-hairpin without interstrand disulfide bonds. This is a novel peptide spatial structure that we propose to name boundless ß-hairpin.

Scoliorhapis stepanovi-new species of sea cucumber from the North-West Pacific (Holothuroidea: Synaptida: Chiridotidae: Taeniogyrinae) and some remarks on the genus Scoliorhapis.

New species Scoliorhapis stepanovi has been collected from depths of 10-23 m on the sandy bottom of Avacha Bay (east coast of Kamchatka), Paramushir Island (North Kuril Islands), and Matua Island (Middle Kuril Islands). It is unique in having sigmoid ossicles in the body wall with points at both ends (without an open-eye, and with the two points lying in a perpendicular plane). Such sigmoids do not occur in any other taeniogyrinid species. The two-pointed sigmoids are 80-115 µm in length, and are scattered in the body wall and not clustered. Probably the two-pointed sigmoids are underdeveloped typical sigmoid with open-eye. In the tentacles there are straight and C-shaped rods, sometimes branched at the ends, 70-90 µm in length. It is assumed that atypical two-pointed sigmoid ossicles may have been originated due to deviating from the usual course of sigmoid development in the middle stages. Scoliorhapis stepanovi resembles S. lindbergi. A key for species of Scoliorhapis is provided.

Identification of unusual peptides with new Cys frameworks in the venom of the cold-water sea anemone Cnidopus japonicus.

Sea anemones (Actiniaria) are intensely popular objects of study in venomics. Order Actiniaria includes more than 1,000 species, thus presenting almost unlimited opportunities for the discovery of novel biologically active molecules. The venoms of cold-water sea anemones are studied far less than the venoms of tropical sea anemones. In this work, we analysed the molecular venom composition of the cold-water sea anemone Cnidopus japonicus. Two sets of NGS data from two species revealed molecules belonging to a variety of structural classes, including neurotoxins, toxin-like molecules, linear polypeptides (Cys-free), enzymes, and cytolytics. High-throughput proteomic analyses identified 27 compounds that were present in the venoms. Some of the toxin-like polypeptides exhibited novel Cys frameworks. To characterise their function in the venom, we heterologously expressed 3 polypeptides with unusual Cys frameworks (designated CjTL7, CjTL8, and AnmTx Cj 1c-1) in E. coli. Toxicity tests revealed that the CjTL8 polypeptide displays strong crustacean-specific toxicity, while AnmTx Cj 1c-1 is toxic to both crustaceans and insects. Thus, an improved NGS data analysis algorithm assisted in the identification of toxins with unusual Cys frameworks showing no homology according to BLAST. Our study shows the advantage of combining omics analysis with functional tests for active polypeptide discovery.